The invention relates to a rapid coupling for connection of an implement to an operating arm and similar, particularly a shovel arm, and the related connecting strap, with at least one pair of lock pins that are movably guided toward each other in alignment and that can be moved toward and away from each other by a drive and that penetrate into an aligned lock hole in the implement in their extended lock position.
Excavators are used for various tasks where there is a need for quick changes of the implements coupled with the boom, such as trench scoop, grabs, hydraulic hammers, wrecking arms and similar, for performance of various tasks. xe2x80x9cImplementsxe2x80x9d, in this connection, also includes implement adaptors, shovel drag bearings and similar.
To connect implements to operating arms, various rapid couplings have already been proposed. Thus, for example, DE-PS 25 11 819 shows a rapid coupling in which the implement is linked through pairs of lock pins, on the one hand, to the end of the shovel arm, and on the other, to be able to swing horizontally, to a connecting strap, where the latter can be operated by means of a pivoted lever mounted on the shovel arm through a hydraulic cylinder to swing the implement, and the lock pins form the swing axis for the work implement. To retract and extend the lock pins, a relatively complicated articulated lever with a linked hydraulic cylinder is provided, and the rapid coupling is relatively expensive overall.
Furthermore, a rapid coupling is known from DE-U-93 15 868 that is integrated into an implement adapter, to couple the corresponding implement to the implement adapter. Such an implement adapter has a disadvantageous impact on the maximum useful load and resultant costs; in addition, changes in the geometry of the implement coupling are possible to only a limited extent.
The known rapid couplings need improvement with regard to their ease of handling. In particular, the coupling of the implement is laborious and generally must be manually assisted, in order to be able to guide the lock pins into their current lock position in the lock holes. But this places the corresponding person in the danger zone of the excavator.
This invention therefore relates to an improved rapid coupling of the type mentioned at the beginning, that avoids the disadvantages of known rapid couplings. In particular, the rapid coupling should be improved with regard to its handling.
According to the invention, this task is solved with a rapid coupling of the type mentioned at the beginning in that pre-centering device are provided to pre-center the retracted lock pins with the lock holes.
An automatic alignment device for the lock pins and the lock holes is provided on the implement, at least to the extent that extension of the lock pins into their lock position is possible. The pre-centering is handled with the lock pins still fully retracted, before they are extended in the pre-centered position. Complete centering can be effected by extending the lock pins, for example, by means of a corresponding conical shape of the lock pins or funnel-shaped introduction bevels on the lock holes. Based on the pre-centered self-alignment of the rapid coupling by means of a movement of the operating arm relative to the implement to be coupled, no manual alignment is necessary. This substantially increases safety since there is no reason to remain in the work area of the excavator.
As a further development of the invention, the pre-centering device form a stop, against which the operating arm can run during its movement relative to the implement. As soon as the coupling section that accepts the lock pins has run against the stop, it is in the coupling position, i.e., the lock pins align with the lock holes. The stop works diagonally to the direction of movement of the lock pins. During coupling, the movement of the operating arm relative to the implement is vertical to the direction of extension of the lock pins, so that the proper position, aligned with the lock holes, is achieved.
A guide to the lock holes is provided particularly for the coupling section on which the lock pins are arranged, where the guide is advantageously formed vertically to the lock holes and forms a stop for the coupling section with the lock pins in said coupling position. While traveling along the guide due to the movement of the operating arm relative to the implement, a stable position corresponding to the coupling position results during the lowering of the guide, in which position the lock pins are aligned with the lock holes. The boom, particularly the end of the corresponding shovel arm or the pertinent connecting strap are placed on the guide, in a particularly simple manner, where the coupling section automatically enters the correct coupling position with the lock holes due to the back and forth motion on the guide.
Pursuant to a preferred embodiment of the invention, the pre-centering device is formed as a web-shaped guide projection, particularly guide strips, arranged in pairs in an implement receptacle in which the coupling section surrounding the lock pins penetrate during coupling. The guide projections project preferably in the direction of motion of the lock pins from the surface of the implement surrounding the lock pins. To achieve the most precise pre-centering possible, each of the lock pins are preferably assigned such a guide projection. The guide projections are particularly marked vertically around the lock holes so that upon pressing the coupling section downward with the lock pins on the projection guides, the pins slide into the proper coupling position. The guide projections or tangents are preferably parallel to each other.
To simplify the insertion of the coupling section with lock pins into the corresponding receptacle on the implement, insertion bevels, acting like funnels, are provided in the further development at the coupling receptacle of the implement and/or at the coupling section surrounding the lock pins. The insertion bevels that, for example, can be formed as a phase on the corresponding edge sections, taper in the direction of insertion of the coupling section into said receptacle on the implement.
The rapid coupling can, in principle, be formed separately from the operating arm, for example, they may be integrated into an implement adapter connected with the operating arm. Preferably, however, the rapid coupling is integrated into the operating arm, particularly its shovel arm, and the related connecting strap. The corresponding implement is therefore coupled directly to the operating arm without a spacer. An adapter, that causes a higher maximum useful load, is not necessary which significantly reduces the price. Another advantage is the ability to change the geometry of the coupling. The distance between the two coupling axes can therefore be changed simply and adjusted to the kinetic requirements, such as, for example, an altered angle or increased force. The lock pins for this are inserted directly into a coupling section of the operating arm, particularly the end sections of the shovel arm and the related connecting strap. Two parallel lock pin pairs are expediently provided that simultaneously act as the hinge pins of two parallel swivel axes for the implement to be coupled. In particular, one pair of pins are placed in the end section of the shovel arm and one pair of pins in the end section of the related connecting strap.
The drive for the extension and retraction of the lock pins can be formed in various manners. Preferably, the lock pins are guided in a rotation-resistant manner into the coupling holes of the corresponding coupling section and provided with left- and right-handed threads into which one spindle connecting the two lock pins is screwed. The spindle can be connected with a drive unit that can actuate the spindle. Preferably, a manual crank drive unit can be mounted on the spindle. If necessary, a motor drive for the spindle can also be provided. Through the simple, slender formation of the drive for the lock pins as a threaded spindle, the lock mechanism can be integrated without problem into the shovel arm and the related connecting strap of the operating arm, without need for large changes in the boom or without resizing this component.
In a further development of the invention, the lock pins and drive can be removed from the coupling holes receiving the same. In particular, they are formed as a one-piece removable cartridge. The lock holes on the implement and the coupling holes into which the lock pins are guided are compatible with conventional pins. This means that instead of the rapid coupling described above, pins for coupling the implement can be steered into it in the conventional manner. This compatibility makes it possible to create the design in such manner that, in mass production, both the lock pins of the rapid coupling and conventional pins can be inserted, with the cost of the components increased only slightly.
According to a further preferred embodiment of the invention, the rotation resistance device, through which the lock pins are introduced into the coupling holes in a rotation-resistant manner, has guides with opposing plate surfaces that penetrate into a longitudinal groove in the lock pins. There is no linear contact between the rotation resistance device and the lock pins due to the plate surfaces. The guides, rather, lie flat on the corresponding wall surface of the guide groove. This also results in only slight surface pressure in the case of rotational forces acting on the lock pins. Wear is substantially reduced, and damage or the deflection of the guide groove into the lock pins is prevented. The lock pins are introduced into the lock holes in a rotatable manner; they form the hinge pins on which the implement swivels. This can result in high rotational forces so that the above plate surfaces are particularly advantageous.
In a further development of the invention, guide pins and annular guide plates surrounding them are provided as rotation resistance, where the plate surfaces are formed on these guide plates. Preferably, two-stage grooves are provided in the lock pins that extend longitudinally along the outer surfaces of the lock pins. The first stage of the guide groove lying radially toward the outside serves to receive the guide plate, while the second, inside stage of the guide groove receives the section of the guide pin extending beyond the plate. In the longitudinal direction of the lock pin, the inside groove has a slight swell to receive the guide pin. It forms a longitudinal stop for the maximum extension of the corresponding lock pin. The rotation resistance device of the lock pin is created, on the other hand, by means of the first stage of the guide groove via the guide plate.
The two-stage formation of the guide groove in the lock pins presents particular advantages: it permits for a more compact arrangement since the larger groove necessarily provided for the guide plate can be open at the inner end of the lock pin. The extension stop is created by the narrower, smaller second stage of the guide groove. Secondly, the guide pin can be placed further from the outlet opening of the coupling hole that accepts the lock pin, while still maintaining the necessary extension path for the lock pin. This makes it possible to provide a seal between the coupling hole and the locking pin at the outer end of the coupling hole, without the guide groove in the lock pin overrunning this seal during extension of the pin.
Catch holes are expediently provided in the lock pins that make those in said screwed-in drive spindle accessible from outside, for example, to be able to insert a manual crank on the drive spindle. Sealing plugs can be inserted, and in particular, screwed into these catch holes in the lock holes from the outside in. This effectively prevents the entry of dirt. In particular, the sealing plugs are free of O rings or other blastomer sealing means, to facilitate use of the rapid coupling even at very high temperatures. Bevel seats can be used to seal the sealing plugs.
To prevent unintentional insertion of the lock pins, for example, as a result of micro-impacts or oscillations, a mechanical insertion stop is provided for the lock pins pursuant to a further preferred embodiment of the invention. The insertion stop positively prevents unintentional insertion of the pins. In principle, the insertion resistance can work directly with the lock pins. Preferably, however, the drive for the lock pins can be blocked by the insertion resistance device in said pins"" extended position, i.e., the insertion resistance works positively on the drive. The pin forces here do not work directly on the insertion resistance device; an effective insertion resistance can be created with minor forces by means of blocking the drive.
The mechanical insertion resistance simultaneously provides a control preventing the lock pins from being fully extended. Preferably, the insertion resistance here is formed in such manner that it can be used or activated only when the lock pins are in their fully extended position. Preferably the insertion resistance here is formed as pins that are used in, particularly screwed into, one of the catch holes of the lock pins. The resistance pin here is dimensioned and placed, with reference to its length, in such manner that it prevents the screwing of the drive spindle into the corresponding lock pin and thus the insertion of the lock pin. The insertion resistance device is expediently formed by the above-described sealing plugs.
To prevent premature wear on the lock pins on the implement to be coupled, particularly as a result of the rotation of the lock pins therein, bushings are provided in a further development of the invention.